Aromatic Acid Lead(Ⅱ)/Lanthanum Coordination Polymers:Synthesis,Structure And Fluorescence Properties Research

In this thesis, six novel lead(II)-based coordination polymers and five lanthanide metal coordination compounds with aromatic polycarboxylates as ligands were obtained through solution isothermal evaporation or hydro thermal methods, structurally determined by single-crystal X-ray diffraction and characterized by elemental analyses, IR spectra, solid-state fluorescence spectrometra and thermogravimetric analyses. The main contents and conclusions are as follows.1. Three lead(Ⅱ)-based coordination polymers,[Pb2(5-CH3-BDC)2]n(1)[Pb(5-OH-BDC)]n·nH2O (2)、[Pb(1,3-phda)(H2O)]n (5), have been synthesized under hydrothermal conditions using m-phthalic acid and m-phenylacetic acid as ligands. The analysis of structure displays that the low dimensional complexes are more likely to form with m-phthalic acid as ligand and the high dimensional complexes are easier to produce with m-phenylacetic acid as ligand.2.[Pb2(5-CH3-BDC)2(phen)2]n·2nH2O (3) and [Pb2(5-CH3-BDC)4(phen)2]n·2nH2O (4) were prepared by introducing o-phenanthroline ligand into5-methylisophthalic acid/Pb system. Compounds (3) shows a chain structure and complex (4) is a binuclear lead(Ⅱ) unit.3. Using2,3-pyrazinedicarboxylic acid as ligands,[Pb3(pzdc)3H2O]n (6) were synthesized through hydrothermal reaction. Structure analysis reveals that ligand pzdc2-acts as three unusual coordinated modes. The ligands connect Pb(II) ions into a trinuclear3-dimensional polymer.4. Compounds (8-10) are prepared by reactions of lanthanum ions with pyridine-2,5-dicarboxylic acid and pyridine-3,5-dicarboxylic acid. Linear pyridine-2,5--dicarboxylic acid is easier to form low dimensional complex than V-type pyridine-3,5--dicarboxylic acid. The length of Ln-O bond are gradually smaller with the order of Ce、 Pr、Nd、Sm、Ho, which is good agreement with lanthanide contraction.5. Solid-state fluorescence experimental analyses at room temperature show that, Compounds (1-10) are good fluorescence performance, while compound (11) has no obvious emission peak which is maybe that the introduction of Ag+ion would quench the emission.